This grant proposal is specifically addressed to the NIH "Academic Research Enhancement Award" (AREA PA-97-052). This proposal has identified strategies to address a significant problem in craniofacial orthopedics, what sorts of forces are involved in moving craniofacial bones, and how best they should be applied. The applicant seeks support for pilot research studies with methods the Principal Investigator has designed. The overall goal of the present proposal is to determine whether compressive cyclic forces with certain characteristics, yet to be determined (here), induce bone resorption more effectively than static forces that compress craniofacial sutures in growing rabbits. A working range of parameters of compressive cyclic and static forces will be determined by quantifying the magnitude, mode and rate of in vivo bone strain induced by these forces in rabbit craniofacial bones. Following chronic loading with selected cyclic and static force parameters, alteration of bone contour in the sagittal dimension will be determined by marker-orientated cephalometric radiography. In vivo bone strain adjacent to craniofacial sutures will be determined, followed by quantification of vital-stained new bone formation in the same sutures by histomorphometric analyses. The proposed studies are anticipated not only to determine the response characteristics of craniofacial bones to selected parameters of cyclic and static forces, but also to correlate mechanical stresses adjacent to craniofacial sutures with the amount of sutural bone resorption. In addition, the anticipated findings will form the basis of addressing the long-term goal of the present research to investigate the effects of a cascade of force parameters on inducing bone resorption in craniofacial bones.